Analgesics are often prescribed to relieve post-operative pain. In recent years, there has been considerable activity directed to methods which permit a patient to receive analgesics in proper doses and at right time so as to effectively decrease the pain that the patient feels.
Infusion pumps are used to administer liquid drugs to patients. The liquid drug is supplied from a drug reservoir and delivered to the patient via an infusion pump. Based on different requirements, the infusion pump can operate in different modes of infusion, such as a pain controlled analgesic (hereinafter PCA) mode. In the PCA mode, the pump is operated to deliver a dose of analgesic to a patient in response to the request by the patient.
The PCA delivery system has a number of advantages including: (1) patients receive medicine when they need it, instead of having to wait for a medical person; (2) time is saved between when the patient feels the pain and when the drug is administered; and (3) a patient receives a proper dose of analgesic, and thus the patient feels less pain. Therefore, reduce the possibility of complications resulting from the pain.
Much research has been done on pneumatic injection micropump:
U.S. Pat. No. 6,408,878 discloses a normally closed type microfabricated elastomeric valve including an elastic microstructure with a width less than 1000 μm, a controlling channel, and a fluidic channel. The elastic microstructure in the fluidic channel is used to block the fluidic channel. While the controlling channel is in a negative status, the elastic microstructure is directed into the controlling channel to allow fluid to pass therethrough. Between closing and opening of the elastic microstructure, it is necessary for the elastic microstructure to deflect the distance of the width of the fluidic channel.
U.S. Pat. No. 7,445,926 provides a fluid control structure in a micro fluid device, which includes a fluidic base plate, a glass substrate and an elastomeric membrane valve disposed between the fluidic base plate and the glass substrate. Due to the elastic nature of the elastomeric membrane, a flowing path of the fluidic layer is normally closed. When a negative pressure is formed in the glass substrate, the elastomeric membrane is directed into a pneumatic manifold of the glass substrate so as to allow fluid to flow thereacross.
Taiwan Patent 1269776 provides a driving microfluid device, which includes a continuously curved pneumatic channel, a membrane and a fluidic channel, wherein the pneumatic channel and the fluidic channel is respectively disposed on the opposing side of the membrane. At the intersection of the pneumatic channel and the fluidic, the membrane is deformed due to the pressure difference, and the fluid is pushed into the fluidic channel.
In the thesis “The study and design of the new membrane-based pneumatic micro-pump” from I-Shou University of Taiwan, a double sided mode peristaltic pump is disclosed, which includes a fluidic channel and a plurality of pairs of side chambers disposed at two opposing sides of the fluidic channel. Actuated by pressure varied in the side chambers, the fluidic channel is deformed to generate transportation of a sample stream. However, to close the fluidic channel efficiently, the pressure applied to the side chamber is large.